Accuracy of machine learning to predict the outcomes of shoulder arthroplasty: a systematic review.

BACKGROUND: Artificial intelligence (AI) uses computer systems to simulate cognitive capacities to accomplish goals like problem-solving and decision-making. Machine learning (ML), a branch of AI, makes algorithms find connections between preset variables, thereby producing prediction models. ML can aid shoulder surgeons in determining which patients may be susceptible to worse outcomes and complications following shoulder arthroplasty (SA) and align patient expectations following SA. However, limited literature is available on ML utilization in total shoulder arthroplasty (TSA) and reverse TSA. METHODS: A systematic literature review in accordance with PRISMA guidelines was performed to identify primary research articles evaluating ML's ability to predict SA outcomes. With duplicates removed, the initial query yielded 327 articles, and after applying inclusion and exclusion criteria, 12 articles that had at least 1 month follow-up time were included. RESULTS: ML can predict 30-day postoperative complications with a 90% accuracy, postoperative range of motion with a higher-than-85% accuracy, and clinical improvement in patient-reported outcome measures above minimal clinically important differences with a 93%-99% accuracy. ML can predict length of stay, operative time, discharge disposition, and hospitalization costs. CONCLUSION: ML can accurately predict outcomes and complications following SA and healthcare utilization. Outcomes are highly dependent on the type of algorithms used, data input, and features selected for the model. LEVEL OF EVIDENCE: III.

Functional characterization of single nucleotide polymorphic variants of DNA repair enzyme NEIL1 in South Asian populations.

The base excision repair (BER) pathway is a precise and versatile mechanism of DNA repair that is initiated by DNA glycosylases. Endonuclease VIII-like 1 (NEIL1) is a bifunctional glycosylase/abasic site (AP) lyase that excises a damaged base and subsequently cleaves the phosphodiester backbone. NEIL1 is able to recognize and hydrolyze a broad range of oxidatively-induced base lesions and substituted ring-fragmented guanines, including aflatoxin-induced 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxyaflatoxin B1 (AFB1-FapyGua). Due to NEIL1's protective role against these and other pro-mutagenic lesions, it was hypothesized that naturally occurring single nucleotide polymorphic (SNP) variants of NEIL1 could increase human risk for aflatoxin-induced hepatocellular carcinoma (HCC). Given that populations in South Asia experience high levels of dietary aflatoxin exposures and hepatitis B viral infections that induce oxidative stress, investigations on SNP variants of NEIL1 that occur in this region may have clinical implications. In this study, the most common South Asian variants of NEIL1 were expressed, purified, and functionally characterized. All tested variants exhibited activities and substrate specificities similar to wild type (wt)-NEIL1 on high-molecular weight DNA containing an array of oxidatively-induced base lesions. On short oligodeoxynucleotides (17-mers) containing either a site-specific apurinic/apyrimidinic (AP) site, thymine glycol (ThyGly), or AFB1-FapyGua, P206L-NEIL1 was catalytically comparable to wt-NEIL1, while the activities of NEIL1 variants Q67K and T278I on these substrates were ≈2-fold reduced. Variant T103A had a greatly diminished ability to bind to 17-mer DNAs, limiting the subsequent glycosylase and lyase reactions. Consistent with this observation, the rate of excision by T103A on 17-mer oligodeoxynucleotides containing ThyGly or AFB1-FapyGua could not be measured. However, the ability of T103A to excise ThyGly was improved on longer oligodeoxynucleotides (51-mers), with ≈7-fold reduced activity compared to wt-NEIL1. Our studies suggest that NEIL1 variant T103A may present a pathogenic phenotype that is limited in damage recognition, potentially increasing human risk for HCC.

Mass Spectrometry-Based Method to Measure Aflatoxin B1 DNA Adducts in Formalin-Fixed Paraffin-Embedded Tissues.

Aflatoxin B1 (AFB1) is a potent human liver carcinogen produced by certain molds, particularly Aspergillus flavus and Aspergillus parasiticus, which contaminate peanuts, corn, rice, cottonseed, and ground and tree nuts, principally in warm and humid climates. AFB1 undergoes bioactivation in the liver to produce AFB1-exo-8,9-epoxide, which forms the covalently bound cationic AFB1-N7-guanine (AFB1-N7-Gua) DNA adduct. This adduct is unstable and undergoes base-catalyzed opening of the guanine imidazolium ring to form two ring-opened diastereomeric 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxy-aflatoxin B1 (AFB1-FapyGua) adducts. The AFB1 formamidopyrimidine (Fapy) adducts induce G → T transversion mutations and are likely responsible for the carcinogenic effects of AFB1. Quantitative liquid chromatography-mass spectrometry (LC-MS) methods have shown that AFB1-N7-Gua is eliminated in rodent and human urine, whereas ring-opened AFB1-FapyGua adducts persist in rodent liver. However, fresh frozen biopsy tissues are seldom available for biomonitoring AFB1 DNA adducts in humans, impeding research advances in this potent liver carcinogen. In contrast, formalin-fixed paraffin-embedded (FFPE) specimens used for histopathological analysis are often accessible for molecular studies. However, ensuring nucleic acid quality presents a challenge due to incomplete reversal of formalin-mediated DNA cross-links, which can preclude accurate quantitative measurements of DNA adducts. In this study, employing ion trap or high-resolution accurate Orbitrap mass spectrometry, we demonstrate that ring-opened AFB1-FapyGua adducts formed in AFB1-exposed newborn mice are stable to the formalin fixation and DNA de-cross-linking retrieval processes. The AFB1-FapyGua adducts can be detected at levels comparable to those in a match of fresh frozen liver. Orbitrap MS2 measurements can detect AFB1-FapyGua at a quantification limit of 4.0 adducts per 108 bases when only 0.8 µg of DNA is assayed on the column. Thus, our breakthrough DNA retrieval technology can be adapted to screen for AFB1 DNA adducts in FFPE human liver specimens from cohorts at risk of this potent liver carcinogen.

Biomechanical Comparison of Ulnar Collateral Ligament Reconstruction Between Palmaris Longus Autograft and Knee Medial Collateral Ligament Allograft.

Background: Medial ulnar collateral ligament (mUCL) injury can cause significant pain and alter throwing mechanics. Common autograft options for mUCL reconstruction (UCLR) include the palmaris longus (PL) and hamstring tendons. Allograft use may reduce donor site morbidity and decrease function related to PL autografts. Purpose: To compare varus stability and load to failure between a novel allograft for UCLR-knee medial collateral ligament (kMCL)-and a PL autograft in human donor elbow specimens. Study Design: Controlled laboratory study. Methods: A total of 24 fresh-frozen human elbows were dissected to expose the mUCL. Medial elbow stability was tested with the mUCL intact (native), deficient, and reconstructed utilizing the humeral single-docking technique with either a (1) kMCL allograft (n = 12) or (2) a PL autograft (n = 12). A 3-N·m valgus torque was applied to the elbow, and valgus rotation of the ulna was recorded via motion tracking cameras. The elbow was cycled through a full range of motion 5 times. After kinematic testing, specimens were loaded to failure at 70° of elbow flexion, and failure modes were recorded. Results: The mUCL-deficient elbows demonstrated significantly greater valgus rotation compared with the intact and reconstructed elbows at every flexion angle tested (10°-120°) (P <.001). Both kMCL- and PL-reconstructed elbows exhibited significantly higher mean valgus rotation compared with the intact state between 10° and 40° of flexion (P < .01). There were no significant differences in valgus rotation at any flexion angle between the kMCL and PL graft groups. When loaded to failure, elbows reconstructed with both kMCL and PL grafts failed at similar torque values (18.6 ± 4 and 18.1 ± 3.4 N·m, respectively; P = .765). Conclusion: Fresh-frozen and aseptically processed kMCL allografts demonstrated similar kinematic and failure properties to PL tendon autografts in UCL-reconstructed elbows, although neither graft fully restored kinematics between 10° and 40°. Clinical Relevance: Prepared kMCL ligament allografts may provide a viable graft material when reconstructing elbow ligaments while avoiding the potential complications related to PL autografts- including donor site morbidity.

Characterization of T-/natural killer cell lymphoproliferative neoplasms associated with systemic, chronic, active Epstein-Barr virus in adults: A report of 5 cases in a Western population.

OBJECTIVES: Because of its low frequency in adult populations and clinical and laboratory overlap with hemophagocytic lymphohistiocytosis and other T-cell lymphomas, T-cell/natural killer (NK) cell systemic, chronic, active Epstein-Barr virus (EBV) (T/NK sCAEBV) infection remains underdiagnosed, preventing critical, prompt therapeutic interventions. METHODS: We report a 5-case series that included 2 adult patients with T/NK sCAEBV and 3 additional adult patients with T/NK lymphomas with concomitant systemic EBV infection to review these entities' overlapping diagnostic and clinical features. RESULTS: Approximately 95% of the world population has been infected with EBV during their lifetime, and infection is usually asymptomatic, with symptomatic cases eventually resolving spontaneously. A small subset of immunocompetent patients develops CAEBV, a life-threatening complication resulting from EBV-infected T-cell or NK cell neoplastic lymphocytes. The sites of end-organ damage in T/NK sCAEBV demonstrate pathologic findings such as reactive lymphoid proliferations, making the diagnosis difficult to establish, with the only curative option being an allogeneic hematopoietic stem cell transplant. CONCLUSIONS: This diagnosis is most prevalent in Asia, with few cases reported in Western countries. Adult age is an independent risk factor for poor outcomes, and most cases are diagnosed in pediatric populations.

Replication Bypass of the N-(2-Deoxy-d-erythro-pentofuranosyl)-urea DNA Lesion by Human DNA Polymerase η.

Urea lesions in DNA arise from thymine glycol (Tg) or 8-oxo-dG; their genotoxicity is thought to arise in part due to their potential to accommodate the insertion of all four dNTPs during error-prone replication. Replication bypass with human DNA polymerase η (hPol η) confirmed that all four dNTPs were inserted opposite urea lesions but with purines exhibiting greater incorporation efficiency. X-ray crystal structures of ternary replication bypass complexes in the presence of Mg2+ ions with incoming dNTP analogs dAMPnPP, dCMPnPP, dGMPnPP, and dTMPnPP bound opposite urea lesions (hPol η·DNA·dNMPnPP complexes) revealed all were accommodated by hPol η. In each, the Watson-Crick face of the dNMPnPP was paired with the urea lesion, exploiting the ability of the amine and carbonyl groups of the urea to act as H-bond donors or acceptors, respectively. With incoming dAMPnPP or dGMPnPP, the distance between the imino nitrogen of urea and the N9 atoms of incoming dNMPnPP approximated the canonical distance of 9 Å in B-DNA. With incoming dCMPnPP or dTMPnPP, the corresponding distance of about 7 Å was less ideal. Improved base-stacking interactions were also observed with incoming purines vs pyrimidines. Nevertheless, in each instance, the α-phosphate of incoming dNMPnPPs was close to the 3'-hydroxyl group of the primer terminus, consistent with the catalysis of nucleotidyl transfer and the observation that all four nucleotides could be inserted opposite urea lesions. Preferential insertion of purines by hPol η may explain, in part, why the urea-directed spectrum of mutations arising from Tg vs 8-oxo-dG lesions differs.

Combined Accentuated Eccentric Loading and Rest Redistribution in High-Volume Back Squat: Acute Stimulus and Fatigue.

ABSTRACT: Chae, S, Long, SA, Lis, RP, McDowell, KW, Wagle, JP, Carroll, KM, Mizuguchi, S, and Stone, MH. Combined accentuated eccentric loading and rest redistribution in high-volume back squat: Acute stimulus and fatigue. J Strength Cond Res 38(4): 648-655, 2024-The purpose of this study was to examine acute stimulus and fatigue responses to combined accentuated eccentric loading and rest redistribution (AEL + RR). Resistance-trained men ( n = 12, 25.6 ± 4.4 years, 1.77 ± 0.06 m, and 81.7 ± 11.4 kg) completed a back squat (BS) 1 repetition maximum (1RM) and weight releaser familiarization session. Three BS exercise conditions (sets × repetitions × eccentric-concentric loading) consisted of (a) 3 × (5 × 2) × 110/60% (AEL + RR 5), (b) 3 × (2 × 5) × 110/60% (AEL + RR 2), and (c) 3 × 10 × 60/60% 1RM (traditional sets [TS]). Weight releasers (50% 1RM) were attached to every first repetition of each cluster set (every first, third, fifth, seventh, and ninth repetition in AEL + RR 5 and every first and sixth repetition in AEL + RR 2). The AEL + RR 5 resulted in greater total volume load (sets × repetitions × eccentric + concentric loading) (6,630 ± 1,210 kg) when compared with AEL + RR 2 (5,944 ± 1,085 kg) and TS (5,487 ± 1,002 kg). In addition, AEL + RR 5 led to significantly ( p < 0.05) greater rating of perceived exertion (RPE) after set 2 and set 3 and lower blood lactate (BL) after set 3 and 5, 15, and 25 minutes postexercise than AEL + RR 2 and TS. There was a main effect of condition for BL between AEL + RR 5 (5.11 ± 2.90 mmol·L -1 ), AEL + RR 2 (6.23 ± 3.22 mmol·L -1 ), and TS (6.15 ± 3.17 mmol·L -1 ). In summary, AEL + RR 5 results in unique stimulus and fatigue responses. Although it may increase perceived exertion, coaches could use AEL + RR 5 to achieve greater back squat total volume load while reducing BL accumulation.

Evaluation of Midazolam-Ketamine-Allopregnanolone Combination Therapy against Cholinergic-Induced Status Epilepticus in Rats.

Status epilepticus (SE) is a life-threatening development of self-sustaining seizures that becomes resistant to benzodiazepines when treatment is delayed. Benzodiazepine pharmacoresistance is thought in part to result from internalization of synaptic GABAA receptors, which are the main target of the drug. The naturally occurring neurosteroid allopregnanolone is a therapy of interest against SE for its ability to modulate all isoforms of GABAA receptors. Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, has been partially effective in combination with benzodiazepines in mitigating SE-associated neurotoxicity. In this study, allopregnanolone as an adjunct to midazolam or midazolam-ketamine combination therapy was evaluated for efficacy against cholinergic-induced SE. Adult male rats implanted with electroencephalographic (EEG) telemetry devices were exposed to the organophosphorus chemical (OP) soman (GD) and treated with an admix of atropine sulfate and HI-6 at 1 minute after exposure followed by midazolam, midazolam-allopregnanolone, or midazolam-ketamine-allopregnanolone 40 minutes after seizure onset. Neurodegeneration, neuronal loss, and neuroinflammation were assessed 2 weeks after GD exposure. Seizure activity, EEG power integral, and epileptogenesis were also compared among groups. Overall, midazolam-ketamine-allopregnanolone combination therapy was effective in reducing cholinergic-induced toxic signs and neuropathology, particularly in the thalamus and hippocampus. Higher dosage of allopregnanolone administered in combination with midazolam and ketamine was also effective in reducing EEG power integral and epileptogenesis. The current study reports that there is a promising potential of neurosteroids in combination with benzodiazepine and ketamine treatments in a GD model of SE. SIGNIFICANCE STATEMENT: Allopregnanolone, a naturally occurring neurosteroid, reduced pathologies associated with soman (GD) exposure such as epileptogenesis, neurodegeneration, and neuroinflammation, and suppressed GD-induced toxic signs when used as an adjunct to midazolam and ketamine in a delayed treatment model of soman-induced status epilepticus (SE) in rats. However, protection was incomplete, suggesting that further studies are needed to identify optimal combinations of antiseizure medications and routes of administration for maximal efficacy against cholinergic-induced SE.

Combined Accentuated Eccentric Loading and Rest Redistribution in High-Volume Back Squat: Acute Kinetics and Kinematics.

ABSTRACT: Chae, S, Long, SA, Lis, RP, McDowell, KW, Wagle, JP, Carroll, KM, Mizuguchi, S, and Stone, MH. Combined accentuated eccentric loading and rest redistribution in high-volume back squat: Acute kinetics and kinematics. J Strength Cond Res 38(4): 640-647, 2024-The purpose of this study was to explore acute kinetic and kinematic responses to combined accentuated eccentric loading and rest redistribution (AEL + RR). Resistance-trained men ( n = 12, 25.6 ± 4.4 years, 1.77 ± 0.06 m, and 81.7 ± 11.4 kg) completed a back squat (BS) 1 repetition maximum (1RM) and weight releaser familiarization session. Three BS exercise conditions (sets × repetitions × eccentric/concentric loading) consisted of (a) 3 × (5 × 2) × 110/60% (AEL + RR 5), (b) 3 × (2 × 5) × 110/60% (AEL + RR 2), and (c) 3 × 10 × 60/60% 1RM (traditional sets [TS]). Weight releasers (50% 1RM) were attached to every first repetition of each cluster set (every first, third, fifth, seventh, and ninth repetition in AEL + RR 5 and every first and sixth repetition in AEL + RR 2). The AEL + RR 5 resulted in significantly ( p < 0.05) greater concentric peak velocity (PV) (1.18 ± 0.17 m·s -1 ) and peak power (PP) (2,304 ± 499 W) compared with AEL + RR 2 (1.11 ± 0.19 m·s -1 and 2,148 ± 512 W) and TS (1.10 ± 0.14 m·s -1 and 2,079 ± 388 W). Furthermore, AEL + RR 5 resulted in significantly greater PV and PP across all 10 repetitions compared with TS. Although AEL + RR 5 resulted in significantly greater concentric mean force (MF) (1,706 ± 224 N) compared with AEL + RR 2 (1,697 ± 209 N) and TS (1,685 ± 211 N), no condition by set or repetition interactions existed. In conclusion, AEL + RR 5 increases PV and PP but has little effect on MF. Coaches might consider prescribing AEL + RR 5 to increase especially peak aspects of velocity and power outcomes.

The aflatoxin B1-induced imidazole ring-opened guanine adduct: High mutagenic potential that is minimally affected by sequence context.

Dietary exposure to aflatoxin B1 (AFB1) is a recognized risk factor for developing hepatocellular carcinoma. The mutational signature of AFB1 is characterized by high-frequency base substitutions, predominantly G>T transversions, in a limited subset of trinucleotide sequences. The 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxyaflatoxin B1 (AFB1-FapyGua) has been implicated as the primary DNA lesion responsible for AFB1-induced mutations. This study evaluated the mutagenic potential of AFB1-FapyGua in four sequence contexts, including hot- and cold-spot sequences as apparent in the mutational signature. Vectors containing site-specific AFB1-FapyGua lesions were replicated in primate cells and the products of replication were isolated and sequenced. Consistent with the role of AFB1-FapyGua in AFB1-induced mutagenesis, AFB1-FapyGua was highly mutagenic in all four sequence contexts, causing G>T transversions and other base substitutions at frequencies of ~80%-90%. These data suggest that the unique mutational signature of AFB1 is not explained by sequence-dependent fidelity of replication past AFB1-FapyGua lesions.

Interaction of mitoxantrone with abasic sites - DNA strand cleavage and inhibition of apurinic/apyrimidinic endonuclease 1, APE1.

Mitoxantrone (1,4-dihydroxy-5,8-bis[2-(2-hydroxyethylamino)ethylamino]-anthracene-9,10-dione) is a clinically-relevant synthetic anthracenedione that functions as a topoisomerase II poison by trapping DNA double-strand break intermediates. Mitoxantrone binds to DNA via both stacking interactions with DNA bases and hydrogen bonding with the sugar-phosphate backbone. It has been shown that mitoxantrone inhibits apurinic/apyrimidinic (AP) endonuclease 1 (APE1)-catalyzed incision of DNA containing a tetrahydrofuran (THF) moiety and more recently, that mitoxantrone forms Schiff base conjugates at AP sites in DNA. In this study, mitoxantrone-mediated inhibition of APE1 at THF sites was shown to be consistent with preferential binding to, and thermal stabilization of DNA containing a THF site as compared to non-damaged DNA. Investigations into the properties of mitoxantrone at AP and 3' α,ß-unsaturated aldehyde sites demonstrated that in addition to being a potent inhibitor of APE1 at these biologically-relevant substrates (∼ 0.5 µM IC50 on AP site-containing DNA), mitoxantrone also incised AP site-containing DNA by catalyzing ß- and ß/δ-elimination reactions. The efficiency of these reactions to generate the 3' α,ß-unsaturated aldehyde and 3' phosphate products was modulated by DNA structure. Although these cell-free reactions revealed that mitoxantrone can generate 3' phosphates, cells lacking polynucleotide kinase phosphatase did not show increased sensitivity to mitoxantrone treatment. Consistent with its ability to inhibit APE1 activity on DNAs containing either an AP site or a 3' α,ß-unsaturated aldehyde, combined exposures to clinically-relevant concentrations of mitoxantrone and a small molecule APE1 inhibitor revealed additive cytotoxicity. These data suggest that in a cellular context, mitoxantrone may interfere with APE1 DNA repair functions.

An intronic RNA element modulates Factor VIII exon-16 splicing.

Pathogenic variants in the human Factor VIII (F8) gene cause Hemophilia A (HA). Here, we investigated the impact of 97 HA-causing single-nucleotide variants on the splicing of 11 exons from F8. For the majority of F8 exons, splicing was insensitive to the presence of HA-causing variants. However, splicing of several exons, including exon-16, was impacted by variants predicted to alter exonic splicing regulatory sequences. Using exon-16 as a model, we investigated the structure-function relationship of HA-causing variants on splicing. Intriguingly, RNA chemical probing analyses revealed a three-way junction structure at the 3'-end of intron-15 (TWJ-3-15) capable of sequestering the polypyrimidine tract. We discovered antisense oligonucleotides (ASOs) targeting TWJ-3-15 partially rescue splicing-deficient exon-16 variants by increasing accessibility of the polypyrimidine tract. The apical stem loop region of TWJ-3-15 also contains two hnRNPA1-dependent intronic splicing silencers (ISSs). ASOs blocking these ISSs also partially rescued splicing. When used in combination, ASOs targeting both the ISSs and the region sequestering the polypyrimidine tract, fully rescue pre-mRNA splicing of multiple HA-linked variants of exon-16. Together, our data reveal a putative RNA structure that sensitizes F8 exon-16 to aberrant splicing.

Efficacy of Lacosamide and Rufinamide as Adjuncts to Midazolam-Ketamine Treatment Against Cholinergic-Induced Status Epilepticus in Rats.

Benzodiazepine pharmacoresistance develops when treatment of status epilepticus (SE) is delayed. This response may result from gamma-aminobutyric acid A receptors (GABAAR) internalization that follows prolonged SE; this receptor trafficking results in fewer GABAAR in the synapse to restore inhibition. Increase in synaptic N-methyl-D-aspartate receptors (NMDAR) also occurs in rodent models of SE. Lacosamide, a third-generation antiseizure medication (ASM), acts on the slow inactivation of voltage-gated sodium channels. Another ASM, rufinamide, similarly acts on sodium channels by extending the duration of time spent in the inactivation stage. Combination therapy of the benzodiazepine midazolam, NMDAR antagonist ketamine, and ASMs lacosamide (or rufinamide) was investigated for efficacy against soman (GD)-induced SE and neuropathology. Adult male rats implanted with telemetry transmitters for monitoring electroencephalographic (EEG) activity were exposed to a seizure-inducing dose of GD and treated with an admix of atropine sulfate and HI-6 1 minute later and with midazolam monotherapy or combination therapy 40 minutes after EEG seizure onset. Rats were monitored continuously for seizure activity for two weeks, after which brains were processed for assessment of neurodegeneration, neuronal loss, and neuroinflammatory responses. Simultaneous administration of midazolam, ketamine, and lacosamide (or rufinamide) was more protective against GD-induced SE compared with midazolam monotherapy. In general, lacosamide triple therapy had more positive outcomes on measures of epileptogenesis, EEG power integral, and the number of brain regions protected from neuropathology compared with rats treated with rufinamide triple therapy. Overall, both drugs were well tolerated in these combination models. SIGNIFICANCE STATEMENT: We currently report on improved efficacy of antiseizure medications lacosamide and rufinamide, each administered in combination with ketamine (NMDAR antagonist) and midazolam (benzodiazepine), in combatting soman (GD)-induced seizure, epileptogenesis, and brain pathology over that provided by midazolam monotherapy, or dual therapy of midazolam and lacosamide (or rufinamide) in rats. Administration of lacosamide as adjunct to midazolam and ketamine was particularly effective against GD-induced toxicity. However, protection was incomplete, suggesting the need for further study.

Effect of Neuromuscular Fatigue on the Countermovement Jump Characteristics: Basketball-Related High-Intensity Exercises.

ABSTRACT: Yoshida, N, Hornsby, WG, Sole, CJ, Sato, K, and Stone, MH. Effect of neuromuscular fatigue on the countermovement jump characteristics: basketball related high-intensity exercises. J Strength Cond Res 38(1): 164-173, 2024-The purpose of this study was to investigate basketball specific neuromuscular (NM) fatigue effect on countermovement jump (CMJ) force-time (F-T) curve characteristics. Eleven male college-level basketball athletes performed 6 CMJ trials at 3 baseline (pre) and 6 postexercise time points. The fatiguing protocol consisted of high-intensity basketball related exercises commensurate with basketball game or practice. Typical CMJ (CMJ-TYP) and phase-specific CMJ variables were derived from the F-T curve. Meaningful differences in CMJ performance were examined using effect size (ES) compared with baseline and previous postexercise time point. Baseline with 3 separated measurements demonstrated suitable CMJ variables reproducibility (CV, coefficient of variation). Most CMJ-TYP output and performance variables displayed substantial alterations immediately postexercise (0 hour) and returned to baseline at 24 hours postexercise, whereas the time and rate-related CMJ-TYP and CMJ-phase variables tended to display delayed decline peaked at 2 hours and delayed recovery to baseline at 48 hours postexercise. In conjunction with the return of the time and rate-related variables, CMJ performance displayed supercompensation at 72 hours postexercise. The results indicate altered NM functions with desired CMJ performance, such as jump height, which imply an altered movement strategy at early stage of recovery process. Full recovery may take 48-72 hours. Practitioners are, therefore, advised to monitor variables reflecting NM functions for precise manipulation of the intensity and volume of exercise to avoid prolonging the recovery from NM fatigue.

A pilot retrospective study of a physician-directed and genomics-based model for precision lifestyle medicine.

Precision lifestyle medicine is a relatively new field in primary care, based on the hypothesis that genetic predispositions influence an individual's response to specific interventions such as diet, exercise, and prescription medications. Despite the increase in commercially available genomic testing, few studies have investigated effects of a physician-directed program to optimize chronic disease using genomics-based precision medicine. We performed an pilot, observational cohort study to evaluate effects of the Wild Health program, a physician and health coach service offering genomics-based lifestyle and medical interventions, on biomarkers indicative of chronic disease. 871 patients underwent genomic testing, biomarker testing, and ongoing health coaching after initial medical consultation by a physician. Improvements in several clinically relevant out-of-range biomarkers at baseline were identified in a large proportion of patients treated through lifestyle intervention without the use of prescription medication. Notably, normalization of several biomarkers associated with chronic disease occurred in 47.5% (hemoglobin A1c [HbA1c]), 33.3% (low density lipoprotein particle number [LDL-P]), and 33.2% (C-reactive protein [CRP]). However, due to the inherent limitations of our observational study design and use of retrospective data, ongoing work will be crucial for continuing to shed light on the effectiveness of physician-led, genomics-based lifestyle coaching programs. Future studies would benefit from implementing a randomized controlled study design, tracking specific interventions, and evaluating physiological data, such as BMI.

Base-Displaced Intercalated Structure of the 3-(2-Deoxy-ß-D-erythropentofuranosyl)-pyrimido[1,2-f]purine-6,10(3H,5H)-dione (6-oxo-M1dG) Lesion in DNA.

The genotoxic 3-(2-deoxy-ß-D-erythro-pentofuranosyl)pyrimido[1,2-α]purin-10(3H)-one (M1dG) DNA lesion arises from endogenous exposures to base propenals generated by oxidative damage and from exposures to malondialdehyde (MDA), produced by lipid peroxidation. Once formed, M1dG may oxidize, in vivo, to 3-(2-deoxy-ß-D-erythropentofuranosyl)-pyrimido[1,2-f]purine-6,10(3H,5H)-dione (6-oxo-M1dG). The latter blocks DNA replication and is a substrate for error-prone mutagenic bypass by the Y-family DNA polymerase hpol η. To examine structural consequences of 6-oxo-M1dG damage in DNA, we conducted NMR studies of 6-oxo-M1dG incorporated site-specifically into 5' -d(C1A2T3X4A5T6G7A8C9G10C11T12)-3':5'-d(A13G14C15G16T17C18A19T20C21A22T23G24)-3' (X = 6-oxo-M1dG). NMR spectra afforded detailed resonance assignments. Chemical shift analyses revealed that nucleobase C21, complementary to 6-oxo-M1dG, was deshielded compared with the unmodified duplex. Sequential NOEs between 6-oxo-M1dG and A5 were disrupted, as well as NOEs between T20 and C21 in the complementary strand. The structure of the 6-oxo-M1dG modified DNA duplex was refined by using molecular dynamics (rMD) calculations restrained by NOE data. It revealed that 6-oxo-M1dG intercalated into the duplex and remained in the anti-conformation about the glycosyl bond. The complementary cytosine C21 extruded into the major groove, accommodating the intercalated 6-oxo-M1dG. The 6-oxo-M1dG H7 and H8 protons faced toward the major groove, while the 6-oxo-M1dG imidazole proton H2 faced into the major groove. Structural perturbations to dsDNA were limited to the 6-oxo-M1dG damaged base pair and the flanking T3:A22 and A5:T20 base pairs. Both neighboring base pairs remained within the Watson-Crick hydrogen bonding contact. The 6-oxo-M1dG did not stack well with the 5'-neighboring base pair T3:A22 but showed improved stacking with the 3'-neighboring base pair A5:T20. Overall, the base-displaced intercalated structure was consistent with thermal destabilization of the 6-oxo-M1dG damaged DNA duplex; thermal melting temperature data showed a 15 °C decrease in Tm compared to the unmodified duplex. The structural consequences of 6-oxo-M1dG formation in DNA are evaluated in the context of the chemical biology of this lesion.

Dissecting telomerase RNA structural heterogeneity in living human cells with DMS-MaPseq.

Telomerase is a specialized reverse transcriptase that uses an intrinsic RNA subunit as the template for telomeric DNA synthesis. Biogenesis of human telomerase requires its RNA subunit (hTR) to fold into a multi-domain architecture that includes the template-containing pseudoknot (t/PK) and the three-way junction (CR4/5). These two hTR domains bind the telomerase reverse transcriptase (hTERT) protein and are thus essential for telomerase catalytic activity. Here, we probe the structure of hTR in living cells using dimethyl sulfate mutational profiling with sequencing (DMS-MaPseq) and ensemble deconvolution analysis. Unexpectedly, approximately 15% of the steady state population of hTR has a CR4/5 conformation lacking features required for hTERT binding. Mutagenesis demonstrates that stabilization of the alternative CR4/5 conformation is detrimental to telomerase assembly and activity. We propose that this misfolded portion of the cellular hTR pool is either slowly refolded or degraded. Thus, kinetic traps for RNA folding that have been so well-studied in vitro may also present barriers for assembly of ribonucleoprotein complexes in vivo.

Training Volume and High-Speed Loads Vary Within Microcycle in Elite North American Soccer Players.

ABSTRACT: Ishida, A, Draper, G, Wright, M, Emerson, J, and Stone, MH. Training volume and high-speed loads vary within microcycle in elite North American soccer players. J Strength Cond Res 37(11): 2229-2234, 2023-The purposes of this study were to reduce dimensionality of external training load variables and examine how the selected variables varied within microcycle in elite North American soccer players. Data were collected from 18 players during 2018-2020 in-seasons. Microcycle was categorized as 1, 2, 3, 4, 5 days before match day (MD-1, MD-2, MD-3, MD-4, and MD-5, respectively). Training load variables included total distance, average speed, maximum velocity, high-speed running distance (HSR), average HSR, HSR efforts, average HSR efforts, sprint distance, average sprint distance, sprint efforts, average sprint efforts, total PlayerLoad, and average PlayerLoad. The first principal component (PC) can explain 66.0% of the variances and be represented by "high-speed load" (e.g., HSR and sprint-related variables) with the second PC relating to "volume" (e.g., total distance and PlayerLoad) accounting for 17.9% of the variance. Average sprint distance and total distance were selected for further analysis. Average sprint distance was significantly higher at MD-3 than at MD-2 (p = 0.01, mean difference = 0.36 m•minute-1, 95% confidence intervals [CIs] = 0.07-0.65 m•minute-1) and MD-4 (p = 0.012, mean difference = 0.26 m•minute-1, 95% CIs = 0.10-0.41 m•minute-1). Total distance was significantly higher at MD-3 than at MD-1 (p < 0.001, mean difference = 1,465 m, 95% CIs = 1,003-1926 m), and MD-2 (p < 0.001, mean difference = 941 m, 95% CIs = 523-1,360 m). Principal component analysis may simplify reporting process of external training loads. Practitioners may need to choose "volume" and "high-speed load" variables. Elite North American Soccer players may accumulate higher average sprint distance at MD-3 than at other training days.

An Analysis of Motivating Factors in 1,725 Worldwide Cases of Mass Murder Between 1900-2019.

Mass murder, particularly mass shootings, constitutes a major, growing public health concern. Specific motivations for these acts are not well understood, often overattributed to severe mental illness. Identifying diverse factors motivating mass murders may facilitate prevention. We examined 1,725 global mass murders from 1900-2019, publicly described in English in print or online. We empirically categorized each into one of ten categories reflecting reported primary motivating factors, which were analyzed across mass murderers generally, as well as between U.S- and non-U.S.-based mass-shooters. Psychosis or disorganization related to mental illness were infrequently motivational factors (166; 9.6%), and were significantly more associated with mass murder committed using methods other than firearms. The vast majority (998, 57.86%) of incidents were impulsive and emotionally-driven, following adverse life circumstances. Most mass murderers prompted by emotional upset were found to be driven by despair or extreme sadness over life events (161, 16.13% within the category); romantic rejection or loss, or severe jealousy (204, 20.44% within the category); some specific non-romantic grudge (212, 21.24% within the category); or explosive, overwhelming rage following a dispute (266, 26.65% within the category). Results suggest that policies seeking to prevent mass murder should focus on criminal history, as well as subacute emotional disturbances not associated with severe mental illness in individuals with poor coping skills who have recently experienced negative life events.